1. Field of the Invention
The present invention relates to an optical module and a computer input apparatus, and more particularly, to an optical module and an optical mouse capable of improving optical recognition.
2. Description of the Prior Art
With the fast progress of the industry of personal computer, applications of the mice have changed from traditional mechanical rolling ball mice to optical mice with optical sensing components. The principle of the traditional mechanical rolling ball mice is very simple and the price is cheap, but dust and dirt are easily brought into the rolling ball causing malfunction as operating of the mouse. It is very inconvenient for users to clear up the rolling ball frequently. The optical mouse with ripe technology and reasonable price has already replaced the traditional mechanical rolling ball mouse gradually. Because the optical mouse dose not need to clear up, difficult to wear and tear, and always keeps a high accuracy for a long time, it has already become the main product in the whole world market.
Please refer to FIG. 1, which is a bottom view of an optical mouse 100 according to the prior art. The optical mouse 100 comprises a bottom surface 12 and a housing 14. The bottom surface 12 includes an opening 16. An optical module (not shown) and an optical sensing device (not shown) are disposed within the optical mouse 100, wherein the optical module is capable of emitting light and projects the light through the opening 16 onto a working plane 11 (shown in FIG. 2) on which the optical mouse 100 is working, and the optical sensing device is capable of comparing a difference between two consecutive images displayed on the working plane 11 by scanning and capturing the images. Every time when the contents of the captured images are changed, the optical mouse 100 uses an inner circuit to calculate moving information (including moving direction and moving distance), and transform them into an axis displacement signal, then transmits via a interface 18 (or wirelessly) to a computer(not shown). The interface 18 is an universal serial bus, USB, or a IEEE 1394, or other interfaces.
Please refer to FIG. 2, which is a side view inside the optical mouse 100 in FIG. 1 according to the prior art. The optical mouse 100 further comprises a light source 20, a light sensing component 21, a circuit board 22, a clipper 23, a light guiding part 24, and a lens 25. The opening 16 is disposed on the bottom surface 12, and an aperture 26 is disposed on the light guiding part 24, and a hole 36 is disposed on the circuit board 22. The opening 16, the aperture 26, and the hole 36 are disposed on an optical path between the light source 20 and the light sensing component 21(shown as the dotted line in FIG. 2). The lens 25 is disposed inside the aperture 26 and below the hole 36. The light sensing component 21 is disposed above the hole 36 of the circuit board 22 and corresponding to the lens 25. The light guiding part 24 includes a first total reflection surface 27 and a second total reflection surface 28 to reflect light 37 emitted by the light source 20 onto the working surface 11. The first total reflection surface 27 protrudes the hole 36 of the circuit board 22 such that the first total reflection surface 27 locates properly between the light source 20 and the light sensing component 21. The clipper 23 prevents the light 37 emitted by the light source 20 from directly emitting to the light sensing component 21, and therefore most parts of the light 37 travels toward the first total reflection surface 27, and is total-reflected by the first total reflection surface 27 to the second total reflection surface 28. After total-reflected by the second total reflection surface 28, the light 37 travels through the opening 16 of the bottom surface 12 to project onto the working surface 11 on which the optical mouse 100 works. The light 37 is scattered and reflected by the working surface 11 and a reflected light 38 travels through the opening 16 and is focused by the lens 25 on the light sensing component 21. By this way, the light sensing component 21 can determine a moving direction and distance of the optical mouse 100 according to a change of the reflected light 38.
The light source 20 is disposed on the circuit board 22, i.e. the relative position of the light source 20 and the light guiding part 24 would change according to such kinds of factors as position, height, inclination thereof, so the position of the working surface 11 which the light 37 illuminates, and the corresponding reflected light 38 would also change. Therefore, the light sensing component 21 which determines the moving direction and distance of the optical mouse 100 according to the changes of the optical mouse 100 would easily produce errors which result in misbehavior of the optical mouse 100. In order to overcome above-mentioned shortcomings, manufacturers of the optical mice 100 must guarantee carefully that all light sources 20 on the circuit board 22 all have the same position, height, and inclination precisely. Thus the optical mice 100 certainly will have higher manufacturing costs. Even so, the light source 20 unavoidably rocks and vibrates when the optical mouse 100 moves on the working surface 11. As aforementioned shortcomings, users of computers really need an improved optical mouse capable of easily fastening the light source 20 and improving optical recognition when the improved optical mouse travels over the working surface 11.